Trunk mains: Consequence of failure

Trunk Mains can cause unacceptable disruption to our customers Addressing trunk main failures

- Root cause analysis
- Trunk main testing
- Trunk mains replacement, relining or duplication
- Monitoring for preventative or rapid response
- Risk analysis and impact assessment
- Innovation investment
- Further research with University of Surrey on probability and corrosion modelling Root cause analysis

• When a major failure occurs, a root cause analysis is undertaken to: — Review all data — Perform detailed operational review — Forensic analysis of any pipe cutout — Non destructive testing of remaining main — Assessment of any external factors

• The aim is to determine the best long-term solution for the main and to learn lessons (to update procedures and standards if needed). Trunk main testing

Site survey/questionnaire and soil testing

Non-destructive testing (NDT)

Laboratory testing of soils

Laboratory testing of pipe material Trunk main monitoring

Risk analysis

Impact assessment

Installation of monitoring allows preventative or rapid response Trunk main risk model

- 4,700km of Trunk Main

- 157,000 simulated burst points spread evenly across this network (at least every 100m).

- Probability of Failure and Consequence of Failure calculated at every one of these simulated burst points. Calculating risk of failure

- Trunk Main Risk Model calculates risk using the corporate risk framework (Cost of Failure) for the following measures:

  - Health & Safety
  - Internal Flooding
  - Pollution
  - Interruption to Supply
  - Low Pressure Leakage & burst detection: Syrinix TrunkMinder Trunk main monitoring tool for leakage and bursts

We’ll be installing approximately another 300 trunk main monitoring units to protect high consequence locations over the next five years. Burst detection: Hydroguard Trunk main monitoring tool for early burst detection

We’ve already installed circa 350 across London and Thames Valley at the highest consequence locations Leakage detection: Sahara

- Highly accurate trunk main mobile leakage detection tool
- Used to find 24ML/d of leakage per year
- Significant investment over next 5 years to install more survey chambers Trunk Mains Strategy: Looking Ahead

Long Term: Reducing risk, development to meet predicted changes in failure

- 100 Year Blueprint
- Innovative Construction method to reduce impact
- Material Analysis Tools
- Data Analysis

Targeting long term replacement

Managing a replacement programme in London